The authors discuss diagnostic and therapeutic aspects of flexion adduction contractures of the thumb - so-called congenital clasped thumb - in patient with distal arthrogryposis type I. The diagnosis is based on classification of distal arthrogryposis elaborated by Hall et al. in 1982. For the prognosis of the deformity and strategy of treatment it is an advantage to divide congenital clasped thumb (CCT) into four groups, as recommended by Weckesser et al. in 1968. The demonstrated patient belongs according to the mentioned criteria into group 2. Associated congenital developmental defects were dealt with in preschool age - a tracheal cyst, inguinal hernias, cryptorchism. Orthopaedic treatment extended over a long period (from 3 months to 12 years); the surgical operations were performed in several stages. The very satisfactory functional results or the reconstruction operations of the hands could not be expressed objectively by EMG examination of the thenar musculature due to hypotrophy and a fixed flexion adduction contracture. Repeated EMG examinations of selected muscles of the upper and lower extremity revealed progression of a neurogenic lesion. An important dermatoglyphic finding was the vertical course of the main papillary lines, the monkey line of the palms and absence of flexional lines of the fingers. Key words: flexion adduction contracture of the thumbs, congenital clasped thumb, distal arthrogryposis, surgery of the hand, electromyography, dermatoglyphs.